A liquefied gas carrier is used to carry liquefied gases such as liquefied natural gas (LNG) or liquefied petroleum gas (LPG) to consumption sites.
A liquefied gas carrier can be divided into an independent tank type and a membrane type depending on storage tank types. The independent tank type does not form an integral structure including a hull and a storage tank together, but has an independent storage tank which is supported by a supporting member of a hull. The independent tank type is divided into Type A, B, C according to a number of barriers to prevent leakage of liquefied gas and pressure. Type A includes aluminum double barrier tank (ADBT) provided by the AKER having both the first and the second barriers. Type B includes self-supporting, prismatic-shape IMO type B which is prismatic type provided by the IHI and a moss type with is spherical shape of the tank having the first barrier and a drip tray to prepare leaking of the first barrier. Type C includes the first barrier as a pressure container. On the other hand, the membrane type tank forms an integral structure including a hull and a storage tank together and is divided into a GTT Mark-III type and a GTT NO 96 type.
Particularly, the independent type tank can be installed to a ship after manufactured separately from the ship, have relatively better structural stability compared to the membrane type tank, and be facilitated to repair and maintain it since the insulation system is exposed to the outside of the tank.
On the other hand, when liquid cargo is transported with various storage tanks, events of leakages of liquid cargo to the outside of the storage tank can be caused due to a variety of reasons such as damages or cracks of the storage tank.
Since when such leakages are caused, it brings large economic losses. Therefore, a great deal of development research is currently under way on fundamentally preventing leakages or re-collecting the leaked liquid, etc.
The most general and widely used technology is installing drip trays at the lower part of the storage tank, and is described for example in KR Publication no 10-2010-0106741.
In this case, there is burden to install a large number of drip trays according to the storage tank structures and sometimes re-install when the position is not accurate. In case of much leakages, more drip trays should be installed, resulting in high cost.
Therefore, there is demand for overcoming such drawbacks described above.